1. Field of the Invention
The present invention relates to a waste heat utilization device for an air compressor that effectively utilizes potential heat of compressed air discharged from the air compressor in order to reduce a power consumption of the air compressor.
2. Description of the Related Art
Compressed air discharged from an air compressor reaches high temperatures of up to 200° C., for example, and therefore, as disclosed in Japanese Patent Application Publication No. 2010-101184, the compressed air is cooled by an aftercooler using cooling water and then cooled further by a refrigeration type dryer using a coolant, whereupon moisture contained in the compressed air is condensed and separated for use. An air compressor main body is thus prevented from overheating by water cooling, air cooling, or the like. An air compressor is one of the machines that consume the greatest amounts of power in a typical factory, and therefore takes up a large proportion of the entire power consumption of the factory. It is therefore desirable to reduce the power consumption of an air compressor.
In a configuration disclosed in Japanese Patent Application Publication No. 2010-101184, a reheater that reheats the compressed air using cooling water heated after cooling the compressed air in the aftercooler is provided on a downstream side of the refrigeration type dryer. By having the reheater reheat the compressed air that has been cooled excessively by the refrigeration type dryer such that a pressure of the compressed air increases again, a load on the air compressor is reduced, leading to a reduction in the power consumption of the air compressor. Japanese Patent Application Publication No. 2010-101184 also discloses a configuration in which cooling water containing thermal energy not consumed by the reheater is transmitted to a boiler facility for use.
In a configuration disclosed in Japanese Patent Application Publication No. 2010-270729, an exhaust heat boiler is provided to generate steam by performing heat exchange between compressed air discharged from an oil free air compressor and supply water so that the supply water evaporates. The heat of the compressed air is then recovered as steam energy.
In the power consumption reduction method disclosed in Japanese Patent Application Publication No. 2010-101184, the heat absorbed by the cooling water in a primary heat exchange between the compressed air and the cooling water in the aftercooler is returned to compressed air in a secondary heat exchange performed in the reheater, and therefore two heat exchange operations are performed. As a result, a heat recovery rate deteriorates. Further, in Japanese Patent Application Publication No. 2010-101184 and Japanese Patent Application Publication No. 2010-270729, potential heat of the compressed air is recovered as steam energy in the boiler, but recovering the potential heat of the compressed air as steam energy does not lead directly to a reduction in the power consumption of the air compressor.